In obtaining a direct positive image using internal latent image type silver halide emulsions, it is effective to use a hydrazine series compound as a nucleating agent and described in, for example, U.S. Pat. No. 4,341,858 and T. H. James, The Theory of the Photographic Process; 4th edition, published by Macmillan Publishers Co., Inc., New York, 1977.
It is known that in a photographic material comprising a support having a low oxygen permeability such as, in particular, a polyester support having coated thereon an internal latent image-type direct positive silver halide emulsion layer, a sufficient image density is not obtained since the nucleating action of the hydrazine compound contained therein in insufficient.
In order to overcome this difficulty, the following methods have been proposed: a method of using a strong oxidizing agent such as a ferricyanide compound for the silver halide emulsion layers as described in Research Disclosure, No. 16929 (1978) and No. 16936 (1978) and a method of using a quinone oxidizing agent for the silver halide emulsion layers as described in the above-described U.S. Pat. No. 4,341,858.
However, the former method results in the problems of deficiency in maximum density and the formation of stain and the latter method results in the problem of the formation of stain in the minimum density portions.